The update utilizes DEB or RPM package manager and only implies adding a new repository, containing new packages. Mind the -2.8 index in the link. If necessary, replace it with the major version number that you want to install, e.g. -2.5, -2.6, -2.7.

For Debian-based Linux (Debian, Ubuntu, Zorin, Elementary)

Add the following line to file /etc/apt/sources.list.d/resilio-agent.list: